Introduction The neuroleptic malignant syndrome and the serotonin syndrome are related and potentially fatal disorders. Their presentation can be similar and treatment is mainly supportive. Case A 63-year-old woman with a history of severe Parkinson's disease presented with an altered mental status, autonomic instability, severe hyperthermia and respiratory failure. There were no signs of infection and she developed a renal function impairment. Her comatose state was persistent and a magnetic resonance imaging scan finally showed bilateral thermal injury in the basal ganglia and cerebellum. She died twelve days after admission. Discussion The neuroleptic malignant syndrome and the serotonin syndrome can be hard to distinguish at clinical presentation. The neuroleptic malignant syndrome is mostly caused by the initiation of antidopaminergic agents but can also be due to an acute shortage of dopaminergic activity as seen in severe Parkinson patients. In these patients this syndrome is often caused by withdrawal of dopaminergic therapy but other triggers have also been described. The time of onset and a careful evaluation of the patient's medical and drug histories are the key to diagnosis and differentiation from related disorders. Causative agents should be abandoned in both syndromes and dopaminergic agonists should be initiated for the neuroleptic malignant syndrome. Conclusion Early recognition is important for the management of the neuroleptic malignant syndrome and the serotonin syndrome. In severe Parkinson patients a variant of the neuroleptic malignant syndrome known as the neuroleptic malignant-like syndrome or the parkinsonism hyperpyrexia syndrome may exist. Copyright © 2012, Nederlandse Vereniging voor Intensive Care. All Rights Reserved.